This invention relates to crystallized glass articles having a surface pattern.
Crystallized glasses formed by the heat-treatment of glasses have attracted a great attension as heat-resistant, incombustible wall materials for buildings and the like because of great mechanical strength, excellent heat resistance and excellent efflorescence resistance.
A crystallized glass article having a desired surface pattern is disclosed in our British Pat. No. 1,427,792.
The crystallized glass article disclosed in the British patent is formed of discrete bodies of crystallizable glass fusion-bonded together along their interfaces, a plurality of adjacent bodies forming a surface layer of the article, each of the bodies having needle-like .beta.-wollastonite crystals, formed by heat-treatment, extending from the surface thereof into the interior thereof in a direction generally perpendicular to the surface of the body, and the crystals extending generally parallel to the surface of the glass article in the region of each interface between a pair of adjacent fusion-bonded bodies and being generally perpendicular to the surface of the glass article between the interfaces, in regions where a surface portion of a body is exposed, whereby a surface pattern defined by the bodies forming the surface layer is provided on the glass article.
The crystallized glass article is obtained by heat-treating discrete bodies of crystallizable glass packed in a mold at a temperature higher than the softening point of the glass but lower than the liquidus temperature thereof, each of the bodies having the property that when heat-treated at a temperature higher than the softening point of the glass but lower than the liquidus temperature thereof needle-like wollastonite crystals are formed, the crystals extending from the surface into the interior of the body in a direction generally perpendicular to the surface of the body while it is being softened and deformed.
The crystallized glass article is non-porous, as will be noted from the specific gravity indicated in TABLE in the specification in the British patent in comparison with the specific gravity of product by rolling method.
When the crystallized glass articles are used as wall plates for buildings, they have disadvantages that they are difficult in transporting and mounting the plates because of their weightness. They have another disadvantage that they are hard to be machined or cut to a desired shape or dimensions because of their hardness.